The invention relates to the steam cooking of food products and, more particularly, to methods and apparatus for steam-cooking shrimp to reduce yield loss and improve their visual appeal.
Methods and apparatus for steam-cooking shrimp at low temperatures, i.e., temperatures below 100° C., to reduce yield loss are disclosed in U.S. Pat. No. 6,274,188, “Method for Steam-Cooking Shrimp at Reduced Temperatures to Decrease Yield Loss,” Aug. 14, 2001. The patent describes a continuous-feed, forced-convection cooker operated with a steam-air mixture at atmospheric pressure at a temperature preferably about 88° C. to decrease the amount of yield lost through evaporation. Such a cooker operated as described works well at reducing the loss of yield of shrimp. But there are problems associated with such low-temperature cooking. First, shrimp and other food products contain an enzyme that causes melanosis, or “black spot” on the shell or outer surface of the food products. In the case of shrimp, as shown in FIG. 1, the black spots 10 detract from the physical appearance of the shrimp 12. Second, cooking at low temperatures can affect the color and, consequently, the appearance of the food product. For example, the appealing pink-orange color of cooked shrimp may not set if the shrimp are cooked at too low a temperature.
Thus, there is a need for cooking shrimp and other food products to reduce yield loss and to enhance their visual appeal.